Don't listen to everything your Paleo-obsessed friends tell you about your early ancestors.
It turns out there's a high likelihood that hominids ate starchy carbohydrates and cooked them too. And, according to new research, we have these foods to thank for our oversized human brains.
While protein has long been acknowledged by evolutionary scientists as essential to the speed of early human brain growth, Spanish researchers found that the high glucose content in previously overlooked starchy carbs -- think cooked tubers like potatoes and yams -- likely played a role as well.
"Although previous studies have highlighted a stone tool-mediated shift from primarily plant-based to primarily meat-based diets as critical in the development of the brain and other human traits," the researchers wrote in their report. "We argue that digestible carbohydrates were also necessary to accommodate the increased metabolic demands of a growing brain."
Pooling archaeological, anthropological, genetic, physiological and anatomical data, researcher Dr. Karen Hardy and her team from the Catalan Institution for Research and Advanced Studies at the Autonomous University of Barcelona explored the coevolution of human use of controlled fire for cooking, the increased variation in our salivary amylase genes (responsible for the early stages of carbohydrate breakdown in the digestive system), and our consumption of said carbohydrates.
Starch is one of the body's largest suppliers of glucose, which is used by every cell as energy. We begin breaking it down from the moment we start chewing, thanks to our amylase enzymes. However, they can only do their jobs effectively when a starch is somewhat cooked. For example, a cooked potato is 20 times more digestible compared to its raw form, evolutionary geneticist Dr. Mark Thomas told The New York Times.
According to Hardy's research team, the human brain uses 25 percent of the body's energy and 60 percent of the glucose available in the blood to function and grow. Connecting the fact that we need such high quantities, which are typically derived from carbohydrates, and the incredible expansion of brain size during our evolution, the researchers believe it's highly unlikely that we could have subsisted on a diet that lacked such resources during this critical time.
There is also biological evidence that the human body began developing additional amylase gene copies (one person can have up to 18 now) to access this form of nutrition more effectively. Primates only have two copies, so that means we completed this digestive evolution within the past 1 million years when we also had access to fire for cooking.
Additional research published last year in The Quarterly Review of Biology noted that there was not one, specific diet plan all hominids followed in the Paleolithic area. It depended on what was available to them in their particular region of the world. While hunter-gatherers in northern climates subsisted heavily on animals, southern climate dwellers likely relied on plants for much of their nutrition. And now we can hypothesize that some of those plants were, indeed, of the starchy variety.
So do yourself a favor and indulge in a few healthy carbs as your body asks for them. It'll do you -- and your brain -- some good.
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